mineral

Amethyst (Geode)

Silicon Dioxide (SiO2) with iron impurities

Hardness: 7 on Mohs scale; Color: Purple, violet, to deep lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Purple, violet, to deep lavender
Luster: Vitreous (glassy)

Identified March 27, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7 on Mohs scale; Color: Purple, violet, to deep lavender; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or cavities (vugs) within igneous rocks, particularly basalt. The purple hue is caused by irradiation of trivalent iron (Fe3+) within the crystal lattice. Most major deposits date back to the Cretaceous period.

Uses & applications

Primary use is in jewelry (faceted or cabochon), ornamental decoration (geodes and cathedrals), and as a popular specimen for mineral collectors.

Geological facts

Until the 18th century, amethyst was included in the cardinal gemstones alongside diamond, ruby, emerald, and sapphire. Large deposits found in Brazil significantly lowered its market value, making it accessible to many collectors.

Field identification & locations

Identify in the field by its distinct purple color, hexagonal prismatic crystal points, and lack of cleavage. Common locations include the Rio Grande do Sul region of Brazil, Artigas in Uruguay, and Ontario, Canada.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral